Posterior antebrachial muscles

Description

The posterior muscles of the antebrachium are divided into two distinct muscle groups. Eight muscles, the lateral group, originate on and around the lateral epicondyle of the humerus, while four shorter muscles, the radial group, descend along the radius to attach on the thumb and index finger of the hand. As the posterior antebrachial muscles cross the posterior side of the wrist, they are held firmly in place by transverse bands called the extensor retinaculum. Surrounding the tendons, as they pass under the retinacular bands, are synovial tendon sheaths that lubricate the tendons and reduce friction. As is common in all muscle compartments, these muscles share much in common. In general, the posterior antebrachial muscles are extensor muscles. They extend the elbow, wrist, and digits. The unique muscle in this group is the brachioradialis. Unlike the other muscles in the posterior compartment, it passes anterior to the elbow and is the lone flexor muscle in this extensor compartment. The radial nerve innervates all of the muscles in the posterior compartment and the radial artery is the major source of blood supply.